Oracle Database bug, table or attempt does not exist, table name contains space

1. Start: fields in the SQL code exported through powderDesiger are in lower case, and then oracle.2.bug is imported directly: The table structure cannot be modified (in PLSQLDeveloper )-

1. Start: fields in the SQL code exported through powderDesiger are in lower case, and then oracle.2.bug is imported directly: The table structure cannot be modified (in PL/SQL Developer )-

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1. Start: the fields in the SQL code exported through powderDesiger are all in lower case and then directly imported to Oracle.

2. bug: The table structure cannot be modified (in PL/SQL Developer) --- including adding deletion and modification...

3. It is clear that the table exists. If you delete it, the table or view does not exist ~!

Row 3 has an error:
ORA-00942: Table or view does not exist

I finally figured out the reason because my table name is in lower case, but in upper case, this problem will not occur.
Under normal circumstances .... the data in the data dictionary is in uppercase, and the dynamic view is in lowercase ........ use "" when using keywords for table or other object names ""

The table name is caused "".
When a table is deleted, cascade constraints deletes the related CONSTRAINTS.

The table to be deleted can be queried using a select statement. The Code is as follows:

II.

1. When a table is generated, the table name is not checked. You can directly create the table. As a result, the table has both primary keys and Foreign keys. You cannot delete the table because of double quotation marks.

2. Report Bugs, invalid characters, or bugs that do not exist in tables or views

3. Solve the problem. Change the table name and delete it.

Code: alter table "TBL_CERT IFICATE _ TYPE" rename to "TABLE2 ";

Here, double quotation marks cause the table name. The double quotation marks have different effects than the previous double quotation marks. The previous double quotation marks indicate the lower-case table name, which leads to a non-consecutive table name.